This is the best scale, IMO. Non magnetic and accurate. They are only sold out of Japan. That is where I ordered mine.
http://www.ebay.com/itm/New-Cartridge-Digital-scale-ortofon-DS-3-From-JP-/161414514295?pt=US_Record_Player_Turntable_Parts&hash=item25950e0677
http://www.ebay.com/itm/New-Cartridge-Digital-scale-ortofon-DS-3-From-JP-/161414514295?pt=US_Record_Player_Turntable_Parts&hash=item25950e0677